Directional Power Control of 5G Radio Base Stations for EMF Compliance – Part I: Design Principles and Feature Validation

When the electromagnetic field (EMF) compliance boundary of a radio base station (RBS) is determined based on the actual maximum EMF exposure condition according to the international standard IEC 62232:2022, software features to monitor and control the time-averaged transmitted power or the equivalent isotropically radiated power (EIRP) are recommended or required in many countries. In this paper, a new software feature that maps the EIRP contributions from massive multiple-input multiple-output (MIMO) RBS to eight azimuthal segments within a cell is presented. The power control is much less often triggered using the new feature than a previous one based on the calculation of the transmitted power only. Furthermore, operators can set the threshold per segment by using the presented feature. The counters associated with the feature provide a conservative estimate of the EIRP in all segments. Part I describes the design principles of the new feature and feature validation tests based on in-situ measurements. The results confirm that the new feature ensures that the time-averaged EIRP is maintained below the set threshold in all test cases. Part II describes time-synchronized measurements for a live network deployment and compares the performance of the described directional feature with the cell-wide feature. The results confirm that the new feature has less impact on the network performance.